The Unreal 3 engine has previously been ported to Flash, but this is the first time a plugin-free (and therefore mobile-friendly) version has been built for the web.

Mozilla is hoping this project will help turn the web into a more serious gaming platform capable of running top-tier console titles.

Combining WebGL, Emscripten, a tool for compiling C++ apps into JavaScript, and the brand new asm.js, Unreal 3 for the web can, according to Mozilla, “rival native performance.”

While the Unreal 3 port is incredibly cool, there are still some stumbling blocks on the path to the web as a top-tier gaming platform, not the least of which is that load times for most games would be massive. Think hours, not minutes, to stream the complex graphics from a server to your mobile device — probably not something anyone particularly wants to sit through.

In other words, while Mozilla and Epic have made some impressive progress bringing Unreal 3 to JavaScript, it’s still going to be a while before you’re playing your favorite console games on the web.

However, Mozilla says it is “working with premium game publishers such as Disney, EA and ZeptoLab who are using the same technology to bring performance optimizations to their top-rated games.” The company is also hoping other browsers will make it possible to run the Unreal engine in their own JavaScript engines. The Chromium project is already discussing just how to do it.

For more on the project and to catch a glimpse of Unreal 3 running in the browser, check out the video below.